You mean pull the immobilizer ecu and swap it? Toyota tells us under no circumstances to ever do this. I took a class on smart key / immobilizer. They say it will cause a serious headache you don't want basically. That being said there is a way to do it, but they do not provide instructions / repair manual information on this because they again do not want us doing it. They want us to put new parts in if need be and there are very specific instructions for the first time you turn on a new ECU.
All that being said... Locksmiths know some "backdoor secrets" that even us mechanics don't, might want to try calling around. To give you an idea where I work its 405$ labor plus a key. Only plus side is its the same labor for just a key, or multiple keys and fobs. I have heard of locksmiths doing it for 100$ + key. Hope this helps